Thin film transistor liquid crystal display (TFT-LCD) is an important flat-panel display device. According to a direction of an electric field for driving liquid crystal molecules, the TFT-LCD is classified into two types: vertical electric field type and horizontal electric field type. For the TFT-LCD of the vertical electric field type, a pixel electrode is formed on an array substrate and a common electrode is formed on an opposite substrate. Typically, the TFT-LCD of TN mode is of the vertical electric field type. For the TFT-LCD of the horizontal electric field type, the pixel electrode and the common electrode both are formed on the array substrate. Typically, the TFT-LCD of Advanced Super Dimension Switch (ADSDS, ADS for short) mode is of the horizontal electric field type. In the ADS mode, a multi-dimensional electric field is formed with both an electric field generated at edges of slit electrodes in a same plane and an electric field generated between a slit electrode layer and a plate-like electrode layer, so that liquid crystal molecules at all orientations, which are provided directly above the electrodes or between the slit electrodes in a liquid crystal cell, can be rotated, In this way, the work efficiency of liquid crystal can be enhanced and the light transmittance can be increased. The ADS mode can improve the image quality of the thin film transistor liquid crystal display and has advantages of high resolution, high transmittance, low power consumption, wide viewing angle, high aperture ratio, low chromatic aberration, high response speed, free of push Mura, etc. Furthermore, the improvements of ADS mode comprise I-ADS technology with a high-transmittance, H-ADS technology with a high aperture ratio, S-ADS technology with a high-resolution and the like.
FIG. 1 is a structural schematic view illustrating the array substrate of the TFT-LCD of ADS mode according to one technique. As shown in FIG. 1, the array substrate mainly comprises a thin film transistor (comprising a gate electrode 1, a gate insulating layer 3, a semiconductor layer 6, a doped semiconductor layer 5, a source electrode 4-1 and a drain electrode 4-2), a first transparent electrode layer 2 (i.e., the common electrode), a first passivation insulating layer 7 and the pixel electrode 8. The thin film transistor is a bottom-gate type thin film transistor, the pixel electrode 8 is connected to the drain electrode 4-2 through a via hole A formed in the first passivation insulating layer 7. During manufacturing the above-mentioned array substrate, five mask processes are generally employed, and in this case, the manufacture process is complicated and the manufacture cost is increased.
In addition, in the TFT-LCD, a black matrix is generally provided on the opposite substrate to prevent light leakage. The opposite substrate and the array substrate are aligned and bonded with each other to form the liquid crystal panel. However, during the process of aligning the array substrate and the opposite substrate, misalignment inevitably occurs and light leakage is resulted. In order to prevent the light leakage caused by the misalignment, the width of the black matrix has to be increased and thus the aperture ratio is reduced.